Background: Using peer mentors to support health-related behavior change may be particularly effective in a VA setting where many patients lack social support on the one hand, but have latent bonds because of shared or similar veteran experiences. The research team has demonstrated that peer mentoring can help African American veterans with hard-to-manage diabetes mellitus improve their glucose control in the short term; however, it is unknown if demonstrated improvements in glucose control persist once mentoring stops and how to best sustain such programs. These are essential questions to address in order to successfully build a generalizable and scalable peer mentor program. This work will build on past and ongoing work with the aim of creating evidence based, low-cost, easy-to-implement peer-mentoring programs that can sustainably support VA PACT efforts. Objectives: The current application seeks to: 1. Test the effectiveness of a self-sustaining peer-mentoring program that trains former peer mentees to be peer mentors to support health-related behavior change in diabetic veterans with poor diabetes control; 2. Assess the effects of becoming a mentor on those who were originally mentees given a growing literature that being a mentor is good for your health; 3. Conduct a rigorous qualitative evaluation examining in-depth the mentor-mentee relationship, the transition to becoming a mentor, and exploring factors relevant to broader program implementation; and 4. Work with a local community based out-patients clinic (CBOC) to implement a peer mentoring program of this nature and perform a formative evaluation of the process. Methods: This study will employ mixed methods. The study will include a randomized controlled trial with two arms: 1. usual care; and 2. peer mentoring where the mentoring comes from former mentees. To understand the impact of being a mentor, potential mentors will also be randomized such that half will become a mentor and half will not. The intervention will be implemented over six months and participants will be followed for an additional twelve months to determine whether effects persist. The outcomes to be assessed include, for both mentees and mentors, glycosylated hemoglobin (HbA1c), blood pressure (BP), low-density lipoprotein (LDL) levels, diabetes quality of life, and depression scores at 6 and 12 months derived from in-person evaluations. Eighteen month assessments will only be of HbA1c, BP, and LDL levels and will be derived from the electronic medical record (EMR). Combined with a process and formative evaluation using in-depth qualitative interviews the study will inform future large scale program implementation. Impacts: Supporting health related behavior change is difficult, frequently costly, and time intensive. As we move toward patient centered care with patient aligned care teams (PACT) it is essential that we find low cost, culturally competent ways to assist our patients outside of the clinical encounter. Relying on the inherent strengths of the veteran community, peer mentoring shows potential as a means to improving outcomes in patients with diabetes. Determining how best to create sustainable peer-mentoring models will create a new powerful tool for the VA with the potential for improving chronic disease outcomes and will demonstrate VA leadership in creating models that can be exported to other health care settings.